Postoperative vault prediction for phakic implantable collamer lens surgery: the LASSO formulae

Abstract

Purpose: To develop and evaluate reliable formulae for predicting post-operative vault more accurately after implantable collamer lens (ICL) surgery in a Caucasian patient population of varying degrees of ammetropia. Setting: Private clinical practice. Design: Retrospective analysis on dataset split in separate training and test set. Methods: One hundred fifteen eyes of 59 patients were used to train regression models predicting post-operative vault based on anterior segment optical coherence tomography parameters (LASSO-OCT formula), ocular biometry data (LASSO-Biometry formula) or data from both devices (LASSO-Full formula). The performance of these models was evaluated against the manufacturer’s nomogram (OCOS) and Nakamura 1 (NK1) and 2 (NK2) formulae on a matched separate test set of 37 eyes of 19 patients. Results: Mean preoperative spherical equivalent was -5.32 ± 3.37 (range: +3.75D to -17.375D). The mean absolute errors of the estimated versus achieved postoperative vault for the LASSO-Biometry, LASSO-OCT and LASSO-Full were 144.1 ± 107.9µm, 145.6 ± 100.6µm and 132.0 ± 86.6µm, respectively. These results were significantly lower compared to the OCOS, NK1 and NK2 formulae (p < 0.006). Postoperative vault could be estimated within 500µm in 97.3% (LASSO-Biometry) to 100% of cases (LASSO-OCT and LASSO-Full). Conclusions: The LASSO suite provides a set of powerful, reproducible yet convenient ICL sizing formulae with state of the art performance in Caucasian patients, including those with low to moderate degrees of myopia. The calculator can be accessed at http://icl.emmetropia.be.